Single 18650 Vs. Stacked 18350 Batteries

[Rixter]

Has anyone here ever compared the performance differences between using a single 18650 battery vs using stacked IMR 18350s? I've been contemplating buying a couple of IMR 18350s after hearing that I'll get better performance when using LR dual-coil cartos in my tanks, but I wanted to see if anyone here has done a side-by-side comparison to see if that's actually true.

I know that stacking batteries is considered by many to be a risky practice, but I've heard that today's IMRs aren't as apt to explode in my face like batteries of old because their chemistry and design (at least in AWs) prohibits it. Since my mod is vented (Sigelei Zmax), I'm fairly confident that it'll be a safe rig, so that's really not a major concern for me. In fact, the Zmax (and the Vamo, for that matter) is designed for use with either a single 18650 or stacked IMR 18350s.

[Uma]

It will up the power, that's a given. Just be sure to keep your batteries in sets... mark them well and don't mix the batches up.

Personally, I stick with the one battery, and just vary my ohms to suit. Double batts still scare me.

[mse12]

I've heard that it keeps the strain on the batteries lower using stacked vs single because the mod is now limiting the power vs boosting it. I do NOT know from experience and please don't take my word and blow yourself up! This is just what I've been hearing/reading recently. A lot of people are having great experiences stacking 18350's in the vamo. I really wish I knew enough about battery chemistry to give a constructive answer. I work with a chemical engineer and will ask him but I doubt he will even know honestly. I work in the rubber industry so I'm not sure about his experience with battery composition. I will post in a few day to let you know his opinion if he even has one.

FWIW stacking IMR batteries is different than stacking CR123A's as they are different chemistry LiMn(IMR) vs LiMnO2(CR123)

I don't know what that means in the operating differences but it is a definitive difference.

Edited January 14, 2013 by mse12

[Rixter]

It's official. Stacked 18350s perform better than a single 18650.

I'd heard that using a single 18650 limits the current to around 2.5 amps, while stacked 18350s allow around 4 amps. All I can say is that when I was using an 18650-powered Zmax in variable power mode with a 1½Ω dual-coil 306 drip atty, there really wasn't much difference in the vape above 13 watts. With stacked 18350s, I've been vaping at 15 watts, and you can definitely tell the difference between 13 watts (6½ watts per coil) and 15 watts (7½ watts per coil). When in variable voltage mode, I can set the Zmax to 4.9v and achieve 16 watts (8 watts per coil) while keeping well below the 4 amp limit (3¼ amps).

This is the best vaping experience I've had to date.

Edited February 2, 2013 by Rixter

[mse12]

Awesome.

[spydre]

Hate to bring up a dead thread, but I read somewhere that stacking the batteries was dangerous, and could possibly cause a short, that rather than stacking, go with a larger battery instead (sort of like the 18650). Is this no longer the case?

[Rixter]

Hate to bring up a dead thread, but I read somewhere that stacking the batteries was dangerous, and could possibly cause a short, that rather than stacking, go with a larger battery instead (sort of like the 18650). Is this no longer the case?

It seems that today's better quality IMR batteries are capable of handling higher current levels than earlier ones, so stacking is not necessary to obtain higher power for dual coil devices. I've never had a problem doing it, but I no longer stack 18350s in my Zmax...no need to anymore.

[Uma]

PLEASE keep them in sets though!!! Do NOT mix them up!! If you lose one of the batteries, toss the other!

Fresh and older batteries charge and discharge at different rates.. it's very very important to keep this in mind at all times.

[JimB]

I have 2 Vamos. I set them at 7 watts. I have tested the single 18650 against the stacked 18350 a couple of different ways. My batteries are AW IMR LiMin. The 18650's are 3800 mah and the 18350's are 800 mah. The first way I tested was to put an 18650 in one Vamo and stacked 18350's in the other. Both have a chi forged drip atty and both at 2.2 ohms resistance. I put a #1 on one and a #2 on the other. Placed them side by side and all day went 1,2,1,2,1,2,1,2 etc. Once in a while I would forget which one was next but not often. When it came time to go to bed I checked my notes and found out that I was on my 3rd 18650 and still had the same set of 18350's. All day without changing them. Then I test the 18650 one day and the 18350's for one day. I had changed the 18650 four times for all day. With the 18350's they still had 6.4v(6.2v is low voltage). I am getting well over 60%more vaping time with the stacked setup. Then I wanted to know a little about how this works. It seems that the overhead on a vv/vw is high managing the RMS controller and the voltage booster. With the stacked setup the you have more than enough power to take care of this overhead. With the single 18650 once a great while it would turn off before low volts and I would have to turn it on again and it would change RMS to AV mode. For 2 weeks now, now problems and only have to change batts once a day. In other forums I have read that some people are afraid about melt down and exploding conditions. First: With the Vamo if it were to explode the end cap is designed to blow out away from you and as far as a melt down that gets down to atty's with less than 1.5 ohms resistance. A lot of people don't seem to realise that if you put dual coils of 1.5 ohms your total resistance is .75 ohms, getting real close to a dead short circuit. If you want 1.5 ohms in a dual atty each coil has to be 3 ohms. resistance in parellel devides. Below 1.5 ohms you are doing serious damage to the life span of the battery.......All that said I love stacked batteries.

[Tom74]

Does anyone know if stacking 18350 batteries in a itaste 134 is safe? Reason im worried about doing it is because its microprocessor controlled and im worried about frying it.

[Rcam1977]

Very interesting thread, looking forward to seeing what the more experienced vapors have to add to this

[fishguy1123]

Not sure Tom, might want to check pbusardo's youtube review. He usually checks that out if it can be done. Just a thought.

[Mr Smith]

I have a pair of ICR 18350's (900mAh/ea) that came with my vamo in a kit with a charger, and a couple of button top IMR 18650's (AW 2000mAh and orbtronic 2900mAh) I run in my vamo v5.

The stacked 18650s seem to get the coil rollin vapor far quicker than the single 18650's. They do however run out of juice and need a recharge quicker, but that is a given considering 1800mAh vs 2000 and 2900 mAh capacities.

They definitely perform better though when they are at full charge. (8.2-8.4v)

That said: Make sure your mod was designed for dual 18350s!!! you don't want to fry your board by doubling the voltage input. Definitely not a good idea in a mech mod without a kick that can handle double voltage input.

Make sure your mod can handle it before you try it.